Characterization amylos-flavour complexes by DSC and X-ray diffraction

Amylose is able to form complexes with a variety of ligands such as fatty acids, emulsifiers and flavour substances. The complex-forming molecules induce the formation of single amylose helices (V amylose). Starch complexation with flavour molecules is one of the mechanisms of flavour retention in starch-containing food systems. Furthermore, the formation of starch-flavour complexes modifies the texture of low-concentration starch systems. In the present investigation, starch-flavour complexes were prepared by combining aqueous potato starch dispersion (2 g/100 g) with decanal and (-)fenchone respectively. The water-insoluble ligands were introduced with the aid of lecithin as non-complexing emulsifier. Flavour molecules other than decanal and (-)fenchone were added directly or dissolved in ethanol. DSC measurements and X-ray powder diffraction were carried out on freeze-dried samples. X-ray diffraction clearly showed the pattern of V amylose, indicating the formation of complexes with different crystalline structures. Endothermic transitions as shown by DSC correlated with the melting of the crystalline amylose-flavour complexes. No correlation was found between the melting temperature measured by DSC and the crystallinity determined by X-ray diffraction.